The dyeing of keratin fibers, including human hair, with dyeing compositions containing oxidation dye precursors, generally called oxidation bases, such as ortho- or para-phenylenediamines, ortho- or para-aminophenols and heterocyclic compounds, is known. These oxidation bases are colorless or weakly colored compounds which, when combined with oxidizing products, can give rise by a process of oxidative condensation to colored compounds.
It is also known that it is possible to vary the shades obtained with these oxidation bases by combining them with dyeing coupling agents or modifiers, the latter being selected, for example, from aromatic meta-diamines, meta-aminophenols, meta-diphenols and certain heterocyclic compounds, such as indole compounds.
The wide range of molecules employed for the oxidation bases and the coupling agents gives a rich palette of colors.
The so-called “permanent” dyeing obtained using these oxidation dyes should, moreover, meet at least one of a certain number of requirements. Thus, it should ideally not cause any problems in toxicological terms, make it possible to obtain shades of the desired intensity, display good resistance to external agents, such as light, weather, washing, permanent waving, sweating and rubbing, provide coverage of white hair, and/or have minimum selectivity, i.e., give the smallest possible differences in coloration all the way along one and the same keratin fiber, which is generally sensitized (i.e. damaged) to a different degree between its tip and its root.
The dyeing of keratin fibers by direct or semi-permanent dyeing is also known. The method traditionally used in direct dyeing comprises applying direct dyes, which are colored and coloring molecules with affinity for the fibers, to the keratin fibers, waiting for a time to allow the colored molecules to penetrate, by diffusion, to the interior of the hairs, and then rinsing the fibers.
In contrast to the compositions for oxidation dyeing, the direct or semi-permanent dyeing compositions are used without the obligatory presence of an oxidizing agent. This dyeing can be carried out repeatedly without degrading the keratin fiber.
For example, the use of nitro benzene, anthraquinone, nitropyridine, azo, xanthene, acridine, azine or triarylmethane direct dyes is known.
The resulting coloration is often chromatic, but is, however, temporary or semi-permanent owing to the nature of the bonds between the direct dyes and the keratin fibers. These interactions mean that the dyes are readily desorbed from the surface and/or the core of the fiber. The coloration generally has poor resistance to washing or to sweating.
There is thus a real need for dyes with better performance, giving improvements in terms of uniformity of coloring, in relation to the quality of the hair that is dyed, shampoo and after-shampoo resistance (tenacity), restriction of scouring which leads to risks of patchiness, and/or color change over time when chromatic dyes are combined which have different respective tenacity.
Furthermore, the use of known cationic direct dyes makes it possible to obtain rich chromatic shades, which are, however, restricted to one color range (yellow, orange, red). Thus, there is a need for dyes outside of the known color range.